The District Attorney's Office is now saying the officers acted lawfully.

It's been more than 18 months since a deadly exchange between Moises Nerio and three members of the Sunnyvale DPS.

Now there's newly-released audio from that day, which shares the moments before the shots were fired.

FULL RECORDING: Newly-released audio of Sunnyvale officer-involved shooting -- WARNING: May be graphic for some

"Stop walking towards me or I'll be forced to shoot you. I don't want to do this. Put the knife down. Stop walking towards me, put the knife down. Put it down right now," the recording says.

In a 44-page report released by the Santa Clara County District Attorney's Office, Deputy DA Lindsay Walsh concluded the officers acted lawfully and they "were left with no other reasonable option, under the totality of the circumstances, but to fire their weapon at Mister Nerio until he no longer posed a threat to them."

This was after the officers made dozens of attempts to de-escalate the situation. They were responding to a call that Nerio had sexually assaulted a relative inside an apartment unit where the shooting took place.

"Come on man, we can work through this, put the knife down. It's not worth it, it's not worth it. Hey! Put the knife down!" was heard on the recording before shots were fired.

SJSU Justice Studies lecturer Greg Woods says transparency is key to restoring trust between police and the public. "The facts of this case will absolutely serve to increase the awareness of the way through which law enforcement officers have been trained to assess threat and respond to that threat," he said.

Nerio's blood alcohol concentration was five times the legal limit to drive. The DA's Office says he also had a history of mental health issues.